This section provides background information related to the present disclosure which is not necessarily prior art.
Heat presses for heat and pressure printing and transfer applications typically include a lower platen and an upper platen that is generally above the lower platen and configured to press down on the lower platen. Typically, a work piece (e.g., fabric or garment) and a heat-activated article (e.g., letters, logos, images, graphics) are positioned on the lower platen while the upper platen is separated from the lower platen. Once the work piece and article are properly positioned, the upper platen is moved vertically down over the lower platen to sandwich the work piece and article between the upper and lower platens. One or both of the platens typically contains a heating element and the platens are typically configured to apply heat and pressure to the work piece and article for a predetermined amount of time (i.e., cure time). After the cure time is completed, the upper platen is lifted up so that the operator can remove the finished product and repeat the steps for the next work piece and article.
On a typical manual heat press, the lower platen is attached to a base structure and the upper platen is attached to a handle and clamping linkage mechanism which is pivotably attached to the base structure to move the electrically heated upper platen between a clamped position, precisely aligned above the lower platen, and an open position spaced apart from the lower platen to allow the operator access to the lower platen. The upper platen is typically moved vertically relative to the lower platen by an operator manipulating the handle. In typical heat presses, the clamping linkage has an over-center locking condition to compress the platens together in the clamped position, bending the steel structure of the press to provide repeatable and predictable clamping force. The handle and linkages can serve to mechanically amplify the operator's strength and can clamp a garment between the upper and lower platen with a clamping force that can be pre-set based on a predetermined thickness of a workpiece and article. Since a specific clamping pressure can be required for each heat transfer application, a mechanical adjustment is typically required to alter the total deflection of the press structure when clamped, thus altering the applied force between the two platens. Automated (i.e., non-manual) heat presses can have similar clamping mechanisms. Thus, typical heat presses require periodic adjustment to maintain a constant clamping force between garments of differing thickness, which can increase operating time and costs.